This invention is related to the field of organometal compound catalysts.
The production of polymers is a multi-billion dollar business. This business produces billions of pounds of polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
One of these technologies is called metallocene catalyst technology. Metallocene catalysts have been known since about 1960. However, their low productivity did not allow them to be commercialized. About 1975, it was discovered that contacting one part water with one part trimethylaluminum to form methyl aluminoxane, and then contacting such methyl aluminoxane with a metallocene compound, formed a metallocene catalyst that had greater activity. However, it was soon realized that large amounts of expensive methyl aluminoxane were needed to form an active metallocene catalyst. This has been a significant impediment to the commercialization of metallocene catalysts.
Borate compounds have been use in place of large amounts of methyl aluminoxane. However, this is not satisfactory, since borate compounds are very sensitive to poisons and decomposition, and can also be very expensive.
It should also be noted that having a heterogeneous catalyst is important. This is because heterogeneous catalysts are required for most modern commercial polymerization processes. Furthermore, heterogeneous catalysts can lead to the formation of substantially uniform polymer particles that have a high bulk density. These types of substantially uniformed particles are desirable because they improve the efficiency of polymer production and transportation. Efforts have been made to produce heterogeneous metallocene catalysts; however, these catalysts have not been entirely satisfactory.
Therefore, the inventors provide this invention to help solve these problems.
An object of this invention is to provide a process that produces a catalyst composition that can be used to polymerize at least one monomer to produce a polymer.
Another object of this invention is to provide the catalyst composition.
Another object of this invention is to provide a process comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce the polymer.
Another object of this invention is to provide an article that comprises the polymer produced with the catalyst composition of this invention.
In accordance with one embodiment of this invention, a process to produce a catalyst composition is provided. The process comprises (or optionally, xe2x80x9cconsists essentially ofxe2x80x9d, or xe2x80x9cconsists ofxe2x80x9d) contacting an organometal compound, an organoaluminum compound, and a treated solid oxide compound to produce the catalyst composition,
wherein the organometal compound has the following general formula:
(X1)(X2)(X3)(X4)M1
wherein M1 is selected from the group consisting of titanium, zirconium, and hafnium;
wherein (X1) is independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls;
wherein substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X1) can be a bridging group which connects (X1) and (X2);
wherein (X3) and (X4) are independently selected from the group consisting of halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein (X2) is selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, substituted fluorenyls, halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein substituents on (X2) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X2) can be a bridging group which connects (X1) and (X2);
wherein the organoaluminum compound has the following general formula:
Al(X5)n(X6)3-n
wherein (X5) is a hydrocarbyl having from 1-20 carbon atoms;
wherein (X6) is a halide, hydride, or alkoxide;
wherein xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive; and
wherein the treated solid oxide compound comprises a halogen, vanadium, and a solid oxide compound;
wherein the halogen is selected from the group consisting of chlorine and bromine;
wherein the solid oxide compound is selected from the group consisting of alumina, aluminophosphate, aluminosilicate, and mixtures thereof.
In accordance with another embodiment of this invention, a process is provided comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce a polymer.
In accordance with another embodiment of this invention, an article is provided. The article comprises the polymer produced in accordance with this invention.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
Organometal compounds used in this invention have the following general formula:
(X1)(X2)(X3)(X4)M1
In this formula, M1 is selected from the group consisting of titanium, zirconium, and hafnium. Currently, it is most preferred when M1 is zirconium.
In this formula, (X1) is independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-Ixe2x80x9d) cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, such as, for example, tetrahydroindenyls, and substituted fluorenyls, such as, for example, octahydrofluorenyls.
Substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) can be selected independently from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffms and olefms. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Substituted silyl groups include, but are not limited to, alkylsilyl groups where each alkyl group contains from 1 to about 12 carbon atoms, arylsilyl groups, and arylalkylsilyl groups. Suitable alkyl halide groups have alkyl groups with 1 to about 12 carbon atoms. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Suitable examples of such substituents are methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloro, bromo, iodo, trimethylsilyl, and phenyloctylsilyl.
In this formula, (X3) and (X4) are independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-IIxe2x80x9d) halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefms. Suitable examples of cyclic groups are cycloparaffms, cycloolefms, cycloacetylenes, and arenes. Currently, it is preferred when (X3) and (X4) are selected from the group consisting of halides and hydrocarbyls, where such hydrocarbyls have from 1 to about 10 carbon atoms. However, it is most preferred when (X3) and (X4) are selected from the group consisting of fluoro, chloro, and methyl.
In this formula, (X2) can be selected from either Group OMC-I or Group OMC-II.
At least one substituent on (X1) or (X2) can be a bridging group that connects (X1) and (X2), as long as the bridging group does not substantially, and adversely, affect the activity of the catalyst composition. Suitable bridging groups include, but are not limited to, aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, phosphorous groups, nitrogen groups, organometallic groups, silicon, phosphorus, boron, and germanium.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefms. Suitable examples of cyclic groups are cycloparaffms, cycloolefins, cycloacetylenes, and arenes. Suitable organometalic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Various processes are known to make these organometal compounds. See, for example, U.S. Pat. Nos. 4,939,217; 5,210,352; 5,436,305; 5,401,817; 5,631,335, 5,571,880; 5,191,132; 5,480,848; 5,399,636; 5,565,592; 5,347,026; 5,594,078; 5,498,581; 5,496,781; 5,563,284; 5,554,795; 5,420,320; 5,451,649; 5,541,272; 5,705,478; 5,631,203; 5,654,454; 5,705,579; and 5,668,230; the entire disclosures of which are hereby incorporated by reference.
Specific examples of such organometal compounds are as follows:
bis(cyclopentadienyl)hafnium dichloride; 
bis(cyclopentadienyl)zirconium dichloride; 
1,2-ethanediylbis(xcex75-1-indenyl)di-n-butoxyhafnium; 
1,2-ethanediylbis(xcex75-1-indenyl)dimethylzirconium; 
3,3-pentanediylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)hafbium dichloride; 
methylphenylsilylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride; 
bis(n-butylcyclopentadienyl)di-t-butylamidohafnium; 
bis(n-butylcyclopentadienyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl)zirconium dichloride; 
nonyl(phenyl)silylbis(1-indenyl)hafnium dichloride; 
dimethylsilylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride; 
dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride; 
1,2-ethanediylbis(9-fluorenyl)zirconium dichloride; 
indenyl diethoxy titanium(IV) chloride; 
(isopropylamidodimethylsilyl)cyclopentadienyltitanium dichloride; 
bis(pentamethylcyclopentadienyl)zirconium dichloride; 
bis(indenyl) zirconium dichloride; 
methyloctylsilyl bis (9-fluorenyl) zirconium dichloride; 
bis-[1-(N,N-diisopropylamino)boratabenzene]hydridozirconium trifluoromethylsulfonate 
Preferably, the organometal compound is selected from the group consisting of
bis(n-butylcyclopentadienyl)zirconium dichloride; 
bis(indenyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl) zirconium dichloride; 
methyloctylsilylbis(9-fluorenyl)zirconium dichloride 
Organoaluminum compounds have the following general formula:
Al(X5)n(X6)3-n
In this formula, (X5) is a hydrocarbyl having from 1 to about 20 carbon atoms. Currently, it is preferred when (X5) is an alkyl having from 1 to about 10 carbon atoms. However, it is most preferred when (X5) is selected from the group consisting of methyl, ethyl, propyl, butyl, and isobutyl.
In this formula, (X6) is a halide, hydride, or alkoxide. Currently, it is preferred when (X6) is independently selected from the group consisting of fluoro and chloro. However, it is most preferred when (X6) is chloro.
In this formula, xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive. However, it is preferred when xe2x80x9cnxe2x80x9d is 3.
Examples of such compounds are as follows:
trimethylaluminum;
triethylaluminum (TEA);
tripropylaluminum;
diethylaluminum ethoxide;
tributylaluminum;
diisobutylaluminum hydride;
tiisobutylaluminum hydride;
triisobutylaluminum; and
diethylaluminum chloride.
Currently, TEA is preferred.
The treated solid oxide compound comprises a halogen, vanadium, and a solid oxide compound. The halogen is selected from the group consisting of chlorine and bromine. Generally, the solid oxide compound is selected from the group consisting of alumina, aluminophosphate, aluminosilicate, and mixtures thereof. Preferably, the solid oxide compound is alumina.
Generally, the surface area of the solid oxide compound is from about 100 to about 1000 m2/g, preferably, from about 200 to about 800 m2/g, and most preferably, from 250 to 600 m2/g.
The pore volume of the solid oxide compound is typically greater than about 0.5 cc/g, preferably, greater than about 0.8 cc/g, and most preferably, greater than 1.0 cc/g.
To produce the treated solid oxide compound, at least one vanadium-containing compound is contacted with the solid oxide compound by any means known in the art to produce a vanadium-containing solid oxide compound. Generally, the solid oxide compound is contacted with an aqueous or organic solution of the vanadium-containing compound prior to calcination. For example, the vanadium can be added to the solid oxide compound by forming a slurry of the solid oxide compound in a solution of the vanadium-containing compound and a suitable solvent such as alcohol or water. Particularly suitable are one to three carbon atom alcohols because of their volatility and low surface tension. A suitable amount of the solution is utilized to provide the desired concentration of vanadium after drying. Drying can be effected by any method known in the art. For example, said drying can be completed by suction filtration followed by evaporation, vacuum drying, spray drying, or flash drying.
Any vanadium-containing compound known in the art that can impregnate the solid oxide compound with vanadium can be used in this invention. The vanadium-containing compound can be selected from the group consisting of vanadium salts and organovanadium compounds. Suitable vanadium salts include, but are not limited to, ammonium vanadate, vanadyl sulfate, vanadium dichloride, vanadium trichloride, and vanadium tetrabromide. Suitable organovanadium compounds include, but are not limited to, vanadium acetylacetonate, vanadium propoxide, vanadium acetate, and mixtures thereof. Generally, the amount of vanadium present in the vanadium-containing solid oxide compound is in a range of about 0.1 to about 10 millimoles per gram of vanadium-containing solid oxide compound before calcining. Preferably, the amount of vanadium present in the vanadium-containing solid oxide compound is in a range of about 0.5 to about 5 millimoles per gram of vanadium-containing solid oxide compound before calcining. Most preferably, the amount of vanadium present in the vanadium-containing solid oxide compound is in a range of about 1 to 3 millimoles per gram of vanadium-containing solid oxide compound before calcining.
After the solid oxide compound is combined with the vanadium-containing compound to produce the vanadium-containing solid oxide compound, it is then calcined for about 1 minute to about 100 hours, preferably from about 1 hour to about 50 hours, and most preferably, from 3 to 20 hours. Generally, the calcining is conducted at a temperature in the range of about 200xc2x0 C. to about 900xc2x0 C., preferably from about 300xc2x0 C. to about 800xc2x0 C., and most preferably, from 400xc2x0 C. to 700xc2x0 C. The calcning can be conducted in any suitable ambient. Generally, the calcining can be completed in an inert atmosphere. Alternatively, the calcining can be completed in an oxidizing atmosphere, such as, oxygen or air, or a reducing atmosphere, such as, hydrogen or carbon monoxide.
After or during calcining, the vanadium-containing solid oxide compound is contacted with a halogen-containing compound. The halogen-containing compound is selected from the group consisting of chlorine-containing compounds and bromine-containing compounds. The halogen-containing compound can be in a liquid phase, or preferably, a vapor phase. The vanadium-containing solid oxide compound can be contacted with the halogen-containing compound by any means known in the art. Preferably, the halogen-containing compound can be vaporized into a gas stream used to fluidize the vanadium-containing solid oxide compound during calcining. The vanadium-containing solid oxide compound is contacted with the halogen-containing compound generally from about 1 minute to about 10 hours, preferably, from about 5 minutes to about 2 hours, and most preferably, from 30 minutes to 3 hours. Generally, the vanadium-containing solid oxide compound is in contact with the halogen-containing compound at a temperature in a range of about 200xc2x0 C. to about 900xc2x0 C., preferably, about 300xc2x0 C. to about 800xc2x0 C., and most preferably, 400xc2x0 C. to 700xc2x0 C. Any type of suitable ambient can be used to contact the vanadium-containing solid oxide compound and the halogen-containing compound. Preferably, an inert atmosphere is used. Alternatively, an oxidizing atmosphere or a reducing atmosphere can be utilized.
Any chlorine-containing compounds or bromine-containing compounds which can impregnate the vanadium-containing solid oxide compound can be used in this invention. Suitable halogen-containing compounds include volatile or liquid organic chloride or bromide compounds and inorganic chloride or bromide compounds. Organic chloride or bromide compounds can be selected from the group consisting of carbon tetrachloride, chloroform, dichloroethane, hexachlorobenzene, trichloroacetic acid, bromoform, dibromomethane, perbromopropane, and mixtures thereof. Inorganic chloride or bromide compounds can be selected from the group consisting of gaseous hydrogen chloride, silicon tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, boron trichloride, thionyl chloride, sulfuryl chloride, hydrogen bromide, boron tribromide, silicon tetrabromide, and mixtures thereof Additionally, chlorine and bromine gas can be used. Optionally, a fluorine-containing compound can also be included when contacting the vanadium-containing solid oxide compound with the halogen-containing compound to achieve higher activity in some cases.
The amount of the halogen present in the treated solid oxide compound is generally in the range of about 2 to about 150% by weight, preferably about 10% to about 100% by weight, and most preferably, 15% to 75% by weight, where the weight percents are based on the weight of the treated solid oxide compound before calcining.
The catalyst compositions of this invention can be produced by contacting the organometal compound, the organoaluminum compound, and the treated solid oxide compound, together. This contacting can occur in a variety of ways, such as, for example, blending. Furthermore, each of these compounds can be fed into a reactor separately, or various combinations of these compounds can be contacted together before being further contacted in the reactor, or all three compounds can be contacted together before being introduced into the reactor.
Currently, one method is to first contact the organometal compound and the treated solid oxide compound together, for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 15xc2x0 C. to 80xc2x0 C., to form a first mixture, and then contact this first mixture with an organoalunminum compound to form the catalyst composition.
Another method is to precontact the organometal compound, the organoaluminum compound, and the treated solid oxide compound before injection into a polymerization reactor for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 20xc2x0 C. to 80xc2x0 C.
A weight ratio of the organoaluminum compound to the treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the treated solid oxide compound to the organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. These ratios are based on the amount of the components combined to give the catalyst composition.
After contacting, the catalyst composition comprises a post-contacted organometal compound, a post-contacted organoaluminum compound, and a post-contacted treated solid oxide compound. It should be noted that the post-contacted treated solid oxide compound is the majority, by weight, of the catalyst composition. Often times, specific components of a catalyst are not known, therefore, for this invention, the catalyst composition is described as comprising post-contacted compounds.
A weight ratio of the post-contacted organoaluminum compound to the post-contacted treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the post-contacted treated solid oxide compound to the post-contacted organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. These ratios are based on the amount of the components combined to give the catalyst composition.
The catalyst composition of this invention has an activity greater than a catalyst composition that uses the same organometal compound, and the same organoaluminum compound, but uses alumina, silica, or silica-alumina that has been impregnated with chloride only as shown in comparative examples 8 and 9. This activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of about 50 to about 150xc2x0 C., and an ethylene pressure of about 400 to about 800 psig. When comparing activities, the polymerization runs should occur at the same polymerization conditions. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
However, it is preferred if the activity is greater than 1000 grams of polymer per gram of treated solid oxide compound per hour, more preferably greater than 2000, even more preferably greater than 3000, and most preferably greater than 5,000. This activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of 90xc2x0 C., and an ethylene pressure of 550 psig. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
In a second embodiment of this invention, the treated solid oxide compound can be post-treated with at least one compound selected from the group consisting of organovanadium compounds, vanadium halide compounds, organotitanium compounds, titanium halide compounds, organoaluminum compounds, organoaluminum halide compounds, and mixtures thereof, as is frequently done in the preparation of Ziegler type catalysts. This process is disclosed in U.S. Pat. No. 4,607,019, which is herein incorporated by reference.
One of the important aspects of this invention is that no aluminoxane needs to be used in order to form the catalyst composition. Aluminoxane is an expensive compound that greatly increases polymer production costs. This also means that no water is needed to help form such aluminoxanes. This is beneficial because water can sometimes kill a polymerization process. Additionally, it should be noted that no borate compounds need to be used in order to form the catalyst composition. In summary, this means that the catalyst composition, which is heterogenous, and which can be used for polymerizing monomers, can be easily and inexpensively produced because of the substantial absence of any aluminoxane compounds or borate compounds. It should be noted that fluoroorganic boron compounds, such as fluorophenyl borate, organochromium compounds, and MgCl2 are not needed in order to form the catalyst composition. Although aluminoxane, borate compounds, fluoroorganic boron compounds, organochromium compounds, or MgCl2 are not needed in the preferred embodiments, these compounds can be used in other embodiments of this invention.
In another embodiment of this invention, a process comprising contacting at least one monomer and the catalyst composition to produce a polymer is provided. The term xe2x80x9cpolymerxe2x80x9d as used in this disclosure includes homopolymers and copolymers. The catalyst composition can be used to polymerize at least one monomer to produce a homopolymer or a copolymer. Usually, homopolymers are comprised of monomer residues, having 2 to about 20 carbon atoms per molecule, preferably 2 to about 10 carbon atoms per molecule. Currently, it is preferred when at least one monomer is selected from the group consisting of ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 3-ethyl-1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and mixtures thereof.
When a homopolymer is desired, it is most preferred to polymerize ethylene or propylene. When a copolymer is desired, the copolymer comprises monomer residues and one or more comonomer residues, each having from about 2 to about 20 carbon atoms per molecule. Suitable comonomers include, but are not limited to, aliphatic 1-olefins having from 3 to 20 carbon atoms per molecule, such as, for example, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, and other olefms and conjugated or nonconjugated diolefins such as 1,3-butadiene, isoprene, piperylene, 2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 1,7-hexadiene, and other such diolefins and mixtures thereof. When a copolymer is desired, it is preferred to polymerize ethylene and at least one comonomer selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. The amount of comonomer introduced into a reactor zone to produce a copolymer is generally from about 0.01 to about 10 weight percent comonomer based on the total weight of the monomer and comonomer, preferably, about 0.01 to about 5, and most preferably, 0.1 to 4. Altematively, an amount sufficient to give the above described concentrations, by weight, in the copolymer produced can be used.
Processes that can polymerize at least one monomer to produce a polymer are known in the art, such as, for example, slurry polymerization, gas phase polymerization, and solution polymerization. It is preferred to perform a slurry polymerization in a loop reaction zone. Suitable diluents used in slurry polymerization are well known in the art and include hydrocarbons which are liquid under reaction conditions. The term xe2x80x9cdiluentxe2x80x9d as used in this disclosure does not necessarily mean an inert material; it is possible that a diluent can contribute to polymerization. Suitable hydrocarbons include, but are not limited to, cyclohexane, isobutane, n-butane, propane, n-pentane, isopentane, neopentane, and n-hexane. Furthermore, it is most preferred to use isobutane as the diluent in a slurry polymerization. Examples of such technology can be found in U.S. Pat. Nos. 4,424,341; 4,501,885; 4,613,484; 4,737,280; and 5,597,892; the entire disclosures of which are hereby incorporated by reference.
The catalyst compositions used in this process produce good quality polymer particles without substantially fouling the reactor. When the catalyst composition is to be used in a loop reactor zone under slurry polymerization conditions, it is preferred when the particle size of the solid oxide compound is in the range of about 10 to about 1000 microns, preferably about 25 to about 500 microns, and most preferably, 50 to 200 microns, for best control during polymerization.
In a more specific embodiment of this invention, a process is provided to produce a catalyst composition, the process comprising (optionally, xe2x80x9cconsisting essentially ofxe2x80x9d, or xe2x80x9cconsisting ofxe2x80x9d):
(1) contacting alumina with an aqueous solution containing vanadyl sulfate to produce a vanadium-containing alumina having from 1 to 3 millimoles of vanadium per gram of vanadium-containing alumina before calcining;
(2) calcning the vanadium-containing alumina at a temperature within a range of 400 to 700xc2x0 C. for 3 to 20 hours to produce a calcined composition;
(3) contacting the calcined composition with carbon tetrachloride for 10 minutes to 30 minutes to produce a chlorided, vanadium-containing alumina having from 15% to 75% by weight chlorine based on the weight of the chlorided, vanadium-containing alumina before calcining;
(4) combining the chlorided, vanadium-containing alumina and bis(n-butylcyclopentadienyl) zirconium dichloride at a temperature within the range of 15xc2x0 C. to 80xc2x0 C. to produce a mixture; and
(5) after between 1 minute and 1 hour, combining the mixture and triethylaluminum to produce the catalyst composition.
Hydrogen can be used with this invention in a polymerization process to control polymer molecular weight.
In addition to the other polymerization parameters already described previously in this disclosure, polymerization can be conducted in the presence of a chlorocarbon activation compound in a reactor zone as is known in the art with vanadium containing catalysts. Suitable chlorocarbon activators include, but are not limited to, chloroform, tetrachloroethane, dichlorodifluoromethane, and mixtures thereof. The concentration of these chlorocarbon activation compounds can vary from a few parts per million (ppm) to a few percent based on the weight of the polymerization diluent. This process is disclosed in U.S. Pat. No. 4,607,019, which is herein incorporated by reference.
One of the features of this invention is that the treated solid oxide compound activates the organometal compound much more efficiently than a oxide compound that does not contain vanadium. Thus, the vanadium contributes to the activation of the organometal compound. A second feature of this invention is that the vanadium-containing solid oxide compound is a polymerization catalyst in it""s own right, providing a high molecular weight component onto an otherwise symmetrical molecular weight distribution of the organometal compound. This component, or skewed molecular weight distribution, imparts higher melt strength and shear response to the polymer than could be obtained from an organometal compound alone. Although the molecular weight breadth, as measured by polydispersity, Mw (weight average molecular weight)/Mn (number average molecular weight), is usually narrow, in the 2.0 to 3.5 range, the shear ratio (high load melt index (HLMI)/melt index (MI)) is larger than obtained in the absence of vanadium, usually about 18 to about 25.
After the polymers are produced, they can be formed into various articles, such as, for example, household containers and utensils, film products, drums, fuel tanks, pipes, geomembranes, and liners. Various processes can form these articles. Usually, additives and modifiers are added to the polymer in order to provide desired effects. It is believed that by using the invention described herein, articles can be produced at a lower cost, while maintaining most, if not all, of the unique properties of polymers produced with metallocene catalysts.